Background: Biomarkers can provide a more accurate measure of long-term intake than can dietary questionnaires. Objective: The objective was to identify which adipose tissue fatty acids are suitable biomarkers of intake as assessed with a validated food-frequency questionnaire. Design: Costa Rican men with a mean (± SD) age of 56 ± 11 y (n = 367) and women aged 60 ± 10 y (n = 136) completed a 135-item food-frequency questionnaire and provided an adipose tissue sample. Fifty fatty acids were identified by capillary gas chromatography. Correlation coefficients were calculated after adjustment for age, sex, body mass index, and smoking status. Results: The best adipose tissue marker for total intake of saturated fatty acids was 15:0 + 17:0 (r = 0.18). Both 15:0 and 17:0 were also the best correlates of dairy product intake (r = 0.31 for each). The diet-adipose tissue correlations for n−3 fatty acids were r = 0.34 for 18:3, r = 0.15 for 20:5, and r = 0.18 for 22:6. Fish intake correlated significantly with these adipose tissue n−3 fatty acids. Dietary and adipose tissue n−6 fatty acids were highly correlated: 18:2 (r = 0.58) and 18:3 (r = 0.24). The best indicators of total trans fatty acid intake were ct18:2n–6 and tc18:2n–6 (r = 0.58 for each); total 18:1 trans fatty acid (r = 0.45) and 16:1 trans fatty acid (r = 0.16) were the next best indicators. Conclusions: Adipose tissue is a suitable biomarker of dietary fatty acid intake, particularly for n−3 and n−6 cis polyunsaturated fatty acids and trans fatty acids. Ideally, adipose tissue and dietary questionnaires should complement, rather than substitute for, each other in epidemiologic studies.

Little is documented about the performance of the food frequency questionnaire (FFQ) in US minority groups and in populations in developing countries. The authors applied a novel technique, the method of triads, to assess the validity and reproducibility of the FFQ among Hispanics. The subjects were men (n = 78) and women (n = 42) living in Costa Rica. Seven 24-hour dietary recalls and two FFQ interviews (12 months apart) were conducted between 1995 and 1998 to estimate dietary intake during the past year. Plasma and adipose tissue samples were collected from all subjects. Validity coefficients, which measure the correlation between observed and “true” dietary intake, were also estimated. The median validity coefficients for tocopherols and carotenoids estimated by dietary recall, the average of the two FFQs, and plasma were 0.71, 0.60, and 0.52, respectively. Compared with adipose tissue, plasma was a superior biomarker for carotenoids and tocopherols. Adipose tissue was a poor biomarker for saturated and monounsaturated fatty acids but performed well for polyunsaturated fatty acids (validity coefficients, 0.45–1.01) and lycopene (validity coefficient, 0.51). This study also showed that biomarkers did not perform better than the FFQ and that they should be used to complement the FFQ rather than substitute for it.

Background: Plasma and adipose tissue concentrations of carotenoids are thought to reflect short- and long-term intakes of carotenoids, respectively. The ability of adipose tissue carotenoid concentrations to reflect dietary intake in population studies is unknown. Objective: We examined the relation between intakes of the major dietary carotenoids and their concentrations in plasma and adipose tissue. Design: A blood sample and an adipose tissue biopsy sample were collected from 115 women and 344 men in Costa Rica after they had fasted overnight, and a dietary interview based on a 135-item food-frequency questionnaire was administered. After carotenoid intake was adjusted for total energy intake and plasma concentrations were adjusted for HDL-, LDL-, and VLDL-cholesterol concentrations, we calculated partial Spearman correlation coefficients that were adjusted for age, sex, smoking, and body mass index. Results: In women, the correlations (r) between intakes and concentrations of α-carotene, β-carotene, β-cryptoxanthin, and lutein+zeaxanthin were 0.25, 0.29, 0.44, and 0.17, respectively (P < 0.05 for r ≥ 0.19), in adipose tissue and 0.26, 0.13, 0.55, and 0.22 in plasma. In men, these values were 0.04, 0.07, 0.23, and 0.06 in adipose tissue and 0.24, 0.22, 0.44, and 0.20 in plasma. In women and men, correlations for lycopene were higher in plasma (r = 0.19 and 0.35, respectively) than in adipose tissue (r = 0.14 and 0.26). The relative abundance of each carotenoid in the diet was similar to its distribution in plasma but not in adipose tissue. Conclusion: The usefulness of adipose tissue and plasma carotenoids as biomarkers of intake is similar, although correlations for individual carotenoids vary substantially.

Background— Intake of long-chain n-3 fatty acids found in fish is low in many countries worldwide. α-Linolenic acid could be a viable cardioprotective alternative to these fatty acids in these countries. Methods and Results— Cases (n=1819) with a first nonfatal acute myocardial infarction and population-based controls (n=1819) living in Costa Rica matched for age, sex, and area of residence were studied. Fatty acids were assessed by gas chromatography in adipose tissue samples and by a validated food frequency questionnaire specifically designed for this population. Odds ratios and 95% confidence intervals were calculated from multivariate conditional logistic regression models. α-Linolenic acid in adipose tissue ranged from 0.36% in the lowest decile to 1.04% in the highest decile. The corresponding median levels of intake were 0.42% and 0.86% energy. Greater α-linolenic acid (assessed either in adipose or by questionnaire) was associated with lower risk of myocardial infarction. The odds ratios for nonfatal myocardial infarction for the highest compared with the lowest deciles were 0.41 (95% confidence interval, 0.25 to 0.67) for α-linolenic acid in adipose tissue and 0.61 (95% confidence interval, 0.42 to 0.88) for dietary α-linolenic acid. The relationship between α-linolenic acid and myocardial infarction was nonlinear; risk did not decrease with intakes >≈0.65% energy (1.79 g/d). Fish or eicosapentaenoic acid and docosahexaenoic acid intake at the levels found in this population did not modify the observed association. Conclusions— Consumption of vegetable oils rich in α-linolenic acid could confer important cardiovascular protection. The apparent protective effect of α-linolenic acid is most evident among subjects with low intakes.

The prevalence of type 2 diabetes has been reaching epidemic proportions across the globe, affecting low/middle-income and developed countries. Two main contributors to this burden are the reduction in mortality from infectious conditions and concomitant negative changes in lifestyles, including diet. We aimed to depict the current state of type 2 diabetes worldwide in light of the undergoing epidemiologic and nutrition transition, and to posit that a key factor in the nutrition transition has been the shift in the type and processing of staple foods, from less processed traditional foods to highly refined and processed carbohydrate sources. We showed data from 11 countries participating in the Global Nutrition and Epidemiologic Transition Initiative, a collaborative effort across countries at various stages of the nutrition-epidemiologic transition whose mission is to reduce diabetes by improving the quality of staple foods through culturally-appropriate interventions. We depicted the epidemiologic transition using demographic and mortality data from the World Health Organization, and the nutrition transition using data from the Food and Agriculture Organization food balance sheets. Main staple foods (maize, rice, wheat, pulses, and roots) differed by country, with most countries undergoing a shift in principal contributors to energy consumption from grains in the past 50 years. Notably, rice and wheat products accounted for over half of the contribution to energy consumption from staple grains, while the trends for contribution from roots and pulses generally decreased in most countries. Global Nutrition and Epidemiologic Transition Initiative countries with pilot data have documented key barriers and motivators to increase intake of high-quality staple foods. Global research efforts to identify and promote intake of culturally-acceptable high-quality staple foods could be crucial in preventing diabetes. These efforts may be valuable in shaping future research, community interventions, and public health and nutritional policies.

Small-size low-density lipoprotein (LDL) cholesterol has been associated with coronary disease in several retrospective case-control studies,^1-6 although other studies have not found this association.^7-10 In fact, in 2 studies, larger LDL particles were associated with increased risk of coronary disease.^7,8 Most prospective studies,^11-13 but not all,¹⁴ also found that patients with coronary disease are more likely than controls to have smaller LDL particles. However, no study, retrospective or prospective, found that small LDL had independent predictive value after adjustment for standard lipid risk factors.^1-6,11-13